Heavy metal pollution in aquatic ecosystems has become one of the global issues. Mollusks such as clams can be used as bioindicators and biomonitors of heavy metal pollution in these ecosystems. In fact, mussels and oysters have been widely used for this purpose. In this study, the concentrations of cadmium were measured in soft tissues of rock oysters )Saccostrea cucullata( collected from two coastal areas along the coast of Laft port. The concentrations were measured using a Perkin Elmer flame AAS after drying, ashing and acid digestion. The mean concentrations of cadmium in oyster tissues were 7.9 and 2.0 µg/g dry weight for these two areas. Considering the qualifications of bioindicator species, bioaccumulation factors )more than one for both areas(, and a comparison of the results with the EPA standard, it was suggested that S. cucullata can be applied as a biological indicator of heavy metals in the aquatic environment.